1. Field of the Invention
The present invention is generally related to a cooling system for a marine propulsion device and, more particularly, to a cooling system that allows cooling water to drain automatically from the cooling system when a marine vessel is removed from the water in which it was operating and the crankshaft of an associated marine engine is generally horizontal.
2. Description of the Related Art
Many different types of drain and flush systems are known to those skilled in the art of marine propulsion devices. In environments where freezing temperatures can be experienced, it is occasionally necessary to remove cooling water from the cooling system of a marine vessel in order to prevent residual amounts of that water from freezing. If residual cooling water freezes within the conduits of the cooling system, two potentially harmful events can occur. First, the frozen cooling water can expand sufficiently to damage the conduit in which the residual water is trapped. Secondly, frozen coolant can create an occlusion that is sufficiently large to block subsequent flow of fluids through a conduit. This type of occlusion can prevent cooling water from circulating through the marine propulsion device when it is subsequently operated. This blockage of the cooling system can deprive heat generating portions of the system from cooling water and, as a result, those portions can overheat and be severely damaged. In order to prevent these two potentially damaging results, the operator of a marine vessel must assure that all cooling water is drained from the system if the vessel is operated or stored in an environment that can experience freezing temperatures.
Many different techniques have been provided in the past which address the problems that can otherwise occur from freezing coolant within the cooling system of a marine propulsion device. Some of these techniques react to decreases in temperature. Others facilitate the draining procedure in order to assist the operator of a marine vessel with the removal of cooling water from the cooling system.
U.S. Pat. No. 5,628,285, which issued to Logan et al. on May 13, 1997, discloses a drain valve for a marine engine. The valve automatically drains water from a cooling system of an inboard marine engine when the ambient temperature drops to a preselected value. The drain valve includes a cup-shaped vase having a group of inlets connected to portions of a cooling system of the engine to be drained, and the open end of the base is enclosed by a cover. Each inlet defines a valve seat and a sealing piston is mounted for movement in the base and includes a series of valve members that are adapted to engage the valve seats.
U.S. Pat. No. 5,902,159, which issued to Killpack et al. on May 11, 1999, describes an inboard/outboard motor cooling system winterizer. The device is intended for flushing or winterizing an inboard/outboard engine cooling system having an open basin for submerging cooling system intake portals in liquid. The basin is capable of being removably and sealably disposed about a sterndrive housing and allowing the sterndrive housing of the motor to pass through the bottom of the basin.
U.S. Pat. No. 5,966,080, which issued to Bigsby on Oct. 12, 1999, discloses a drain plug warning system. The system includes a first member that can be attached to a transom or other wall of a watercraft and a second member that is shaped to be received within an aperture that is formed through the first member. The drain water from the watercraft, the drain plug or second member is removed from the aperture of the first member, and water is allowed to drain through the aperture. If the second member is not replaced within the aperture to a predetermined location relative to the first member, a magnetically sensitive component near the aperture assumes a state that will cause an alarm under certain predefined conditions such as when an operator activates a key switch mechanism of the watercraft.
U.S. Pat. No. 5,980,342, which issued to Logan et al. on Nov. 9, 1999, discloses a flushing system for a marine propulsion engine. The system provides a pair of check valves that are used in combination with each other. One of the check valves is attached to a hose located between the circulating pump and the thermostat housing of the engine. The other check valve is attached to a hose through which fresh water is provided.
U.S. Pat. No. 6,050,867, which issued to Shields et al. on Apr. 18, 2000, discloses a drain system for a marine vessel. The system is provided for a marine vessel in which three types of drain operations can be performed at one common location near the transom of the marine vessel. A multiple conduit structure is provided with a plurality of fluid passages extending at least partially through its structure. A first fluid passage allows the bilge of the boat to be drained. A second fluid passage allows multiple locations on the engine to be drained through a common port.
U.S. Pat. No. 6,089,934, which issued to Biggs et al. on Jul. 18, 2000, discloses an engine cooling system with simplified drain and flushing procedure. The system is provided with one or more flexible conduits attached to drain openings of the engine and its related components. First ends of the conduits are attached to the drain openings while the second ends are sealed by studs attached to a plate of a stationary bracket. A retainer is slidably associated with the flexible conduits and attached to a tether which in turn is attached to a handle. By manipulating the handle, the tether forces the retainer to slide along the flexible conduits and control the position of the second ends of the flexible conduits.
U.S. Pat. No. 6,135,064, which issued to Logan et al. on Oct. 24, 2000, discloses an engine drain system. The engine cooling system is provided with a manifold that is located below the lowest point of the cooling system of an engine. The manifold is connected to the cooling system of the engine, a water pump, a circulation pump, the exhaust manifolds of the engine, and a drain conduit through which all of the water can be drained from the engine.
U.S. Pat. No. 6,343,965 which issued to Biggs et al. on Feb. 5, 2002, discloses a pneumatically actuated marine engine water drain system. The system is provided which includes one or more pressure actuated valves associated with the coolant water drain system. The boat operator is provided with a pressure controller that allows pressure to be introduced into the system for the purpose of actuating the drain valves and, as a result, opening various drain conduits to allow cooling water to drain from the engine cooling system into the bilge or overboard.
U.S. Pat. No. 6,374,849, which issued to Howell on Apr. 23, 2002, describes a test cock apparatus with freeze protection capability. The apparatus is intended for controlling fluid pressure and flow in a backflow preventer valve. It includes a valve housing having interior walls defining a chamber therein and including an inlet port and a discharge port communicating with the chamber for permitting fluid flow therethrough. A temperature responsive freeze protection element is positioned within the chamber and is axially movable between a closed position in sealing engagement with the interior walls of the valve housing for preventing fluid flow through the discharge port and an open position out of sealing engagement with the walls of the valve housing for permitting passage of fluid through the discharge port.
U.S. Pat. No. 6,379,201, which issued to Biggs et al. on Apr. 30, 2002, discloses a marine engine cooling system with a check valve to facilitate draining. A ball moves freely within a cavity formed within the valve. Pressurized water, from a sea pump, causes the ball to block fluid flow through the cavity and forces pumped water to flow through a preferred conduit which may include a heat exchanger. When the sea pump is inoperative, the ball moves downward within the cavity to unblock a drain passage and allow water to drain from the heat generating components of the marine engine.
U.S. Pat. No. 6,390,870, which issued to Hughes et al. on May 21, 2002, discloses a marine engine cooling system with simplified water drain and flushing mechanism. A manifold is located at a low portion of the cooling system to allow all of the water within the cooling system to drain through a common location, or manifold. A rigid shaft is connected to a valve associated with the manifold and extended upwardly from the manifold to a location proximate the upper portion of the engine so that a marine vessel operator can easily reach the upper end of the shaft and manipulate the shaft to open the valve of the manifold.
U.S. Pat. No. 6,439,939, which issued to Jaeger on Aug. 27, 2002, discloses a siphon inhibiting device for a marine cooling system. A valve comprises first and second portions of a housing structure and a buoyant member disposed within the housing structure for movement along a first axis between an inlet port and an outlet port. The buoyant member is shaped to have a cylindrical portion and another portion which is shaped in the form of a frustum of a cone. Upward movement of the buoyant member causes an elastomeric seal on the buoyant member to come into contact with an internal lip formed in the housing structure, thereby creating a seal that prevents an upward flow of water in a direction from the outlet port to the inlet port.
U.S. Pat. No. 6,506,085, which issued to Casey et al. on Jan. 14, 2003, discloses a pump and drain apparatus for a marine propulsion system. An integral pump and drain apparatus is contained in a common housing structure to reduce the required space needed for these components in the vicinity proximate the engine of a marine propulsion system. The valve of the drain is remotely actuated by air pressure and therefore does not require the boat operator to manually remove plugs or manually actuate mechanical components to cause the engine to drain through the drain conduit that is formed as an integral part of the housing structure.
U.S. Pat. No. 6,582,263, which issued to Jaeger et al. on Jun. 24, 2003, discloses a marine exhaust elbow structure with enhanced water drain capability. The elbow is provided with a stainless steel tube within a water outlet opening to assure that a drain opening remains open even when the exhaust elbow is exposed to a corrosive environment. Since cast iron tends to expand in volume as a result of corrosion of its surface areas, water outlet openings intended to perform a draining function can be partially or fully closed as a result of corrosion. The insertion of a stainless steel tube in one or more water outlet openings of the exhaust elbow assures that an internal water cavity of the elbow can drain when the associated internal combustion engine is turned off, thereby minimizing the possibility of freeze damage to the exhaust components.
U.S. Pat. No. 6,645,024, which issued to Zumpano on Nov. 11, 2003, describes a fresh water marine engine flushing assembly and system. Fresh water is supplied from an onboard water supply which can also serve as the water supply for drinking, galley appliances, showers, toilets, etc. A path of fluid flow is disposed in fluid communication between the maintained water supply and the marine engine and communicates therewith by an adapter assembly which is preferably permanently secured to the marine engine. A flush valve assembly is remotely controlled and preferably electronically activated so as to regulate the flow of cooling water through the cooling system, in the conventional manner, or fresh water from the maintained water supply for purposes of removing salt water remnants and contaminants.
U.S. Pat. No. 6,912,895, which issued to Jaeger on Jul. 5, 2005, discloses a coolant flow monitoring system for an engine cooling system. The monitor is removably connectable in serial fluid communication with a coolant conduit of an engine cooling system. By providing a flow restrictor between upstream and downstream ports, a differential pressure is created between the upstream and downstream ports. The measured magnitude of this differential pressure allows a microprocessor, or similarly configured component, to determine the actual flow rate of the coolant passing through the coolant conduit between the upstream and downstream pressure sensing ports. In this way, actual flow is measured to indicate the proper operation of the cooling system.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
In known marine propulsion systems which incorporate a sterndrive and an engine within the marine vessel, draining of the cooling system requires the opening of valves and/or drain plugs to allow water to drain from the system. Typically, water within the marine vessel is allowed to drain into the bilge from where it is later removed by a bilge pump.
It would therefore be significantly beneficial if a marine propulsion system could be provided in which the removal of the marine vessel from a body of water automatically provides for the draining of all lake water or sea water from the cooling system without the need to remove plugs or otherwise manually cause water to drain from the cooling system. It would also be beneficial if this type of system allowed all the water to automatically drain from both the portions of the cooling system within the marine vessel and the cooling conduits located behind the transom of the marine vessel and associated with the marine drive unit.